It is well-known that by trimming a mast in the fore or aft direction, the lever arm of the moment which causes heeling can be decreased to overcome the tendency of the sailboat to sail into the wind. This becomes particularly important when sailing in heavy winds where the rudder is relied upon to resist heeling and the tendency of the sailboat to sail into the wind.
According to one known method of trimming a mast which utilizes hydraulic cylinders to connect the fore and aft stays to the hull, trimming is achieved in two steps by trial and error through releasing the tension in one stay by discharging hydraulic fluid from the associated cylinder, and by increasing the tension in the other stay by supplying the associated hydraulic cylinder with hydraulic fluid. With this method, it is difficult to achieve the desired tension in the stays because the hydraulic cylinders are supplied and exhausted independently of each other in a two step operation. Moreover, during such trial and error adjustment, the shape of the sail undergoes change providing less windward performance and impaired sailing efficiency. This is particularly significant in racing.